Most households don't think about the box that brings internet into the home until something breaks. But the equipment matters for both performance and cost. A modem translates the ISP's signal into data your devices can use; a router steers that data to individual devices over Wi-Fi or Ethernet. A gateway simply combines both functions in one unit, which is why ISPs often provide them.
Engadget's guide says ISP-supplied gateways tend to be cheap, lowest-common-denominator hardware, often limited to Wi-Fi 6 and non-mesh configurations. That can be fine for basic use, but it may not deliver the speed or coverage of newer Wi-Fi 6E/7 gear or a mesh system. Users can often put the ISP equipment into bridge mode and connect their own router.
Cost is a key business consideration. The article cites AT&T's All-Fi Pro as an example: $25 per month on top of an existing plan for Wi-Fi 7 and mesh extenders. That adds up to $300 in a year, and for less than two years of rental fees, a household could own a mesh system outright and take it to another provider. If an ISP still charges equipment rental, buying your own can save money and offer more flexibility.